基于统计过程控制的两阶段缓冲监控方法

当前市场环境快速变化且竞争愈发激烈,通过有效控制不确定性以避免进度延迟是项目管理者极为重视的方面.关键链缓冲管理提供了一种应对项目进度风险的有效方法,针对现有缓冲监控机制存在的忽视活动层面不确定信息以及项目动态执行特征的不足,提出一种基于统计过程控制的两阶段统计缓冲监控方法(SBMA).第1阶段通过在活动层面设置管理者认为可以接受的活动工期波动范围,生成项目层面基于缓冲消耗指标的容忍阈值,建立统计缓冲控制图;第2阶段依据假设检验理论,当缓冲消耗指标超出缓冲控制图中监控阈值时即触发相应行动.模拟实验结果表明,相对于已有研究中的其他3种缓冲监控方法, SBMA可以更准确及时地给出项目整体进度预警信息,并且可以更有效地追溯至活动层面识别出活动工期是否发生异常波动,从而验证所提出方法的实用性和优越性.

Two-stage buffer monitoring method based on statistical process control

In today''s highly competitive and rapidly changing marketplace, project managers attach great importance to dealing with the uncertainty in order to avoid schedule disruptions. The critical chain scheduling and buffer management (CC/BM) technique has shown to provide an effective approach for coping with schedule variability. Yet, the current buffer monitoring mechanism faces a problem of neglecting the related activity uncertainty information and the dynamic feature of the project execution. In order to overcome these deficiencies, this paper develops a new two-stage buffer monitoring approach(SBMA) based on a statistical process control procedure. In the first phase, our approach allows the user to set the duration variation that is acceptable on the activity level, which will result in tolerance limits of the buffer consumption at the project level in the form of a statistical buffer control chart(SBCC) by using Monte Carlo simulation. In the second phase, the observations of schedule deviations measured by the buffer consumption can be plotted against the tolerance limits on the SBCC, and the corresponding action decisions can be derived by using the hypothesis testing theory. A computational experiment has been set up to compare the capability of the proposed SBMA versus the existing traditional/relative/dynamic buffer monitoring approach in the literature. The results demonstrate that the SBMA can report warning signals more accurately and hence trigger control actions more timely, while maintaining a comparatively high probability of successful detections. Besides, the SBMA is more capable of differentiating between variations that are either acceptable or unacceptable in the duration of the individual activities.